Show group address in group metadata

Signed-off-by: Thomas Citharel <tcit@tcit.fr>

lib/service/metadata/actor.ex

@@ -1,10 +1,12 @@
 defimpl Mobilizon.Service.Metadata, for: Mobilizon.Actors.Actor do
+  alias Phoenix.HTML
   alias Phoenix.HTML.Tag
   alias Mobilizon.Actors.Actor
+  alias Mobilizon.Web.JsonLD.ObjectView
   alias Mobilizon.Web.MediaProxy
 
   def build_tags(%Actor{} = actor, _locale \\ "en") do
-    tags = [
+    [
       Tag.tag(:meta, property: "og:title", content: Actor.display_name_and_username(actor)),
       Tag.tag(:meta, property: "og:url", content: actor.url),
       Tag.tag(:meta, property: "og:description", content: actor.summary),
@@ -12,7 +14,12 @@ defimpl Mobilizon.Service.Metadata, for: Mobilizon.Actors.Actor do
       Tag.tag(:meta, property: "profile:username", content: actor.preferred_username),
       Tag.tag(:meta, property: "twitter:card", content: "summary")
     ]
+    |> maybe_add_avatar(actor)
+    |> maybe_add_group_schema(actor)
+  end
 
+  @spec maybe_add_avatar(list(Tag.t()), Actor.t()) :: list(Tag.t())
+  defp maybe_add_avatar(tags, actor) do
     if is_nil(actor.avatar) do
       tags
     else
@@ -20,4 +27,17 @@ defimpl Mobilizon.Service.Metadata, for: Mobilizon.Actors.Actor do
         [Tag.tag(:meta, property: "og:image", content: actor.avatar.url |> MediaProxy.url())]
     end
   end
+
+  defp maybe_add_group_schema(tags, %Actor{type: :Group} = group) do
+    tags ++ [~s{<script type="application/ld+json">#{json(group)}</script>} |> HTML.raw()]
+  end
+
+  defp maybe_add_group_schema(tags, _), do: tags
+
+  # Insert JSON-LD schema by hand because Tag.content_tag wants to escape it
+  defp json(%Actor{} = group) do
+    "group.json"
+    |> ObjectView.render(%{group: group})
+    |> Jason.encode!()
+  end
 end